Field of the Invention
The invention relates to a contactless chip card.
Chip cards, that is to say plastic cards which contain a semiconductor chip, are nowadays mostly of a contact-dependent structure. In order to use the chip card, it has to be inserted into a reader, which establishes an ohmic contact for communication between a terminal and the card.
However, contactless chip cards have also already become known and are also already in use. In the case of such cards, contact with a terminal takes place through a capacitive or inductive coupling, that is to say through an electric or magnetic component of an electric magnetic field. The inductive coupling is preferably used in that case.
In the case of an inductive coupling, a certain minimum coupling factor between a coil of the chip card and a coil of the terminal is necessary. The coupling factor depends on the size of the terminal coil, the distance of the card from the latter, the relative position in relation to the latter and the size of the coil in the card. The larger the coil in the card, the generally greater the coupling factor. Therefore, it is generally desired to make the coil in the card as large as possible. However, the coil has to be electrically connected to the chip in the chip card. In such cases a coil with a large surface area leads to technically complex assembly solutions, but in particular to difficult handling during transport. It would be much more simple to produce and handle small coils which are about the size of the conventional contact modules of the contact-dependent chip cards. However, if that were the case the coupling factor at a given distance would be significantly less or, for the same coupling factor, the range would be considerably reduced.
A chip card which is known from Published Netherlands Patent Application NL 9100347 has a semiconductor chip that is connected to a first conductor loop having at least one winding. The cross-sectional area of the loop has approximately the same dimensions as the semiconductor chip. Moreover, the data carrier configuration has at least one second conductor loop with at least one winding, a cross-sectional area with approximately the same dimensions as the data carrier configuration and a region which forms a third loop with approximately the same dimensions as the first conductor loop. The first and second conductor loops are coupling inductively to one another through the third conductor loop.
However, in that device, the first and third conductor loops are connected to one another through a magnetic yoke, which entails complicated and therefore expensive mounting of the semiconductor chip in the card.